Why do printers (e.g. Epson R3000) need to switch between black inks instead of using them in parallel?

Question

The Epson R3000 has cartridges for both Photo Black and Matte Black.

Both cartridges are physically in the printer at the same time, but if you want to switch from using one to the other, you need to make that choice in a menu and it will use up some ink switching from one to the other.

Just out of curiosity: how come they don't just provide both blacks side by side, in the same way e.g. cyan and magenta are available side by side without having to switch one out?

Are the black inks special in some significant way?

Answer 1

Money, hardware price, attractiveness.

The heads of printers (you'll need one for each color) aren't that cheap. Based on the printer design those are either part of the cartridge itself or separated (and connected to the ink cartridge through a thin pipe).

While I haven't looked up your printer, I assume it's having separated heads, since otherwise you wouldn't be able to switch the ink on the fly. So just look up the black printer head in an online store. You'd need one more of these. The "switch" mechanism wouldn't be there of course, but instead you'd need another tray etc. so prices here should be similar.

They obviously consider the ink lost during switching cheaper for the consumer (or they just consider it a convenient way to get you into buying ink more frequently).

Edit: Out of curiosity I still looked it up on Amazon:

That's quite a tiny selection of colors... :)

That's a total of 9 different cartridges with colors. I assume the printer has 4 different printer heads (cyan, magenta, yellow, and black). Without the color switching you'd need more than twice the number of printer heads. Also remember that you'll have to clean them from time to time if they're not in use (which could be horribly long, assuming you only print your christmas photos every year or something like that). So overall, I guess reusing the heads based on the job might indeed be the better solution. Remember that cleaning heads wastes some ink as well (probably even more than switching).

Edit 2: To answer your question regarding the "just reusing without cleaning": I guess that could cause quality issues, like the first few lines (based on the image to be printed) using the wrong color. The two blacks are indeed different inks. Imagine ordering a car in metallic black and one fender being matte black. You wouldn't like that. I'm not sure what the other grayish cartridges are for though, maybe someone else could elaborate a bit more on those :)